1. Field of the Invention.
The present invention relates to a coating apparatus for directly or indirectly applying a liquid or pasty medium onto a moving layer of material, e.g., paper or cardboard (or carton). The coating apparatus includes a dispenser implement as well as a spreading device for finely controlling the amount or thickness of the applied medium.
2. Description of the Related Art.
A coating apparatus as described above typically consists of a dispenser implement that applies the liquid or pasty substance onto a moving layer of either paper or cardboard (or carton) in combination with a spreading device for finely controlling an amount of a previously applied medium, is known to exist in numerous variations. The dispersion implements are often, e.g., in the form of some kind of open jet nozzle applicators, for example. The spreading devices to control the amounts of applied medium, on the other hand, are usually equipped with some kind of wiper or blade.
The so-called direct application is performed in such a way that the layer of material, for example paper, carton, cardboard, or any sort of textile fabric, first moves past the opening of the dispenser implement and subsequently past the spreading device for finely adjusting the amount of the applied liquid or pasty substance while the moving layer itself is supported from behind by, e.g., a counter roll.
The indirect application, on the other hand, is accomplished in such a way that the liquid or pasty medium is first applied onto a dispersion roll, where a spreading device controls its amount and or thickness on the surface of the dispersion roll. After the substance is spread to the appropriate thickness it is finally transferred from the surface of the dispersion roll onto the moving layer of material.
One of the main disadvantages of conventional methods of applying substances onto moving layers is the general complexity of the overall construction of this sort of coating apparatus with all the necessary components.
What is needed in the art is a fully functional coating apparatus of the above-described type that produces high quality applications of liquid or pasty mediums, but which is constructed in a much simpler way.